Wednesday, April 30, 2008

Leidy is known as the "Father of American Vertebrate Paleontology". He described the first relatively complete dinosaur skeleton, Hadrosaurus, and introduced many American and European scientists to the fossil riches of the American West. Leidy's consummate skill in comparative anatomy would allow him to identify and characterize even the most fragmentary fossil material.

Leidy was also the "Founder of American Parasitology," a Professor of Anatomy at the University of Pennsylvania, a pioneering protozoologists, an influential teacher of Natural History, an accomplished microscopist and scientific illustrator, and an expert on a variety of subjects encompasing the earth and natural sciences. He published scientific papers on more than a thousand extinct and living protozoa, fungi and invertebrates and vertebrates as well as an assortment of publications on human biology and medicine. He was also one of the earliest supporters of Charles Darwin.

The argon-argon dating method has been widely used to determine the age of rocks, whether they're thousands or billions of years old. Nevertheless, the technique had systematic errors that produced dates with uncertainties of about 2.5%.

Scientists have lowered this uncertainty to 0.25 percent and brought it into agreement with other isotopic methods of dating rocks, such as uranium/lead dating. As a result, argon-argon dating today can provide more precise absolute dates for many geologic events, ranging from volcanic eruptions and earthquakes to the extinction of the dinosaurs and many other creatures at the end of the Cretaceous period and the beginning of the Tertiary period. That boundary had previously been dated at 65.5 million years ago, give or take 300,000 years.

The best date for the Cretaceous-Tertiary, or K/T, boundary is now 65.95 million years, give or take 40,000 years.

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Argon-argon dating, developed at UC Berkeley in the 1960s, is based on the fact that the naturally-occurring isotope potassium-40 decays to argon-40 with a 1.25-billion-year half-life. Single-grain rock samples are irradiated with neutrons to convert potassium-40 to argon-39, which is normally not present in nature. The ratio of argon-39 to argon-39 then provides a measurement of the age of the sample.

Molecular analysis of a shred of 68-million-year-old Tyrannosaurus rex protein – along with that of 21 modern species – confirms that dinosaurs share common ancestry with chickens, ostriches, and to a lesser extent, alligators. The work represents the first use of molecular data to place a non-avian dinosaur in a phylogenetic tree that traces the evolution of species. The scientists also report that similar analysis of 160,000- to 600,000-year-old collagen protein sequences derived from mastodon bone establishes a close phylogenetic relationship between that extinct species and modern elephants.

The ecology of Cambrian communities was remarkably modern, with networks of feeding relationships among marine species that lived hundreds of millions of years ago being remarkably similar to those of today.

The food web of the Burgess Shale from the Middle Cambrian; spheres represent species or groups of species, and the links between them show feeding relationships. The drawing shows a top predator, Anomalocaris, chasing one of its likely prey species, the trilobite Olenoides, with arrows indicating their positions in the food web. Image: N. D. Martinez

The researchers compiled data from the 505 million-year-old Burgess Shale in British Columbia, Canada and the even earlier Chengjiang Shale of eastern Yunnan Province, China, dating from 520 million years ago. Both fossil-rich assemblages are unusual because they have exquisitely preserved soft-body parts for a wide range of species. They determined who was eating whom by piecing together a variety of clues. There was the occasional smoking gun, such as fossilized gut contents in the carnivorous, cannibalistic priapulid worm Ottoia prolifica. However, in most cases, feeding interactions were inferred from where species lived and what body parts they had. For example, grasping claws, swimming lobes, big eyes, and toothy mouthparts suggest that Anomalocaris canadensis, a large, unusual organism with no modern descendents, was a formidable predator of trilobites and other arthropods, consistent with bite marks found on some fossils.

The Cambrian food webs share many similarities with modern webs, such as how many species are expected to be omnivores or cannibals, and the distribution of how many types of prey each species has. Such regularities, and any differences, become apparent only when variation in the number of species and links among webs is accounted for. "There are a few intriguing differences with modern webs, particularly in the earlier Chengjiang Shale web. However, in general, it doesn't seem to matter what species, or environment, or evolutionary history you've got, you see many of the same sorts of food-web patterns," explains Dunne.

Researchers have published the most extensive survey to date of African mitochondrial DNA (mtDNA). Over 600 complete mtDNA genomes from indigenous populations across the continent show that these early human populations were small and isolated from each other for many tens of thousands of years.

MtDNA, inherited down the maternal line, was used to discover the age of the famous 'mitochondrial Eve' in 1987. This work has since been extended to show unequivocally that the most recent common female ancestor of everyone alive today was an African woman who lived in the past 200,000 years. Paleontology provides corroborating evidence that our species originated on this continent approximately 200,000 years ago.

The migrations after 60,000 years ago that led modern humans on their epic journeys to populate the world have been the primary focus of anthropological genetic research, but relatively little is known about the demographic history of our species over the previous 140,000 years in Africa. The current study returns the focus to Africa and in doing so refines our understanding of early modern Homo sapiens history.

Doron Behar, Rambam Medical Center, Haifa, said: “We see strong evidence of ancient population splits beginning as early as 150,000 years ago, probably giving rise to separate populations localized to Eastern and Southern Africa. It was only around 40,000 years ago that they became part of a single pan-African population, reunited after as much as 100,000 years apart.”

Recent paleoclimatological data suggests that Eastern Africa went through a series of massive droughts between 135,000-90,000 years ago. It is possible that this climatological shift contributed to the population splits. What is surprising is the length of time the populations were separate - as much as half of our entire history as a species.

The timing of these events coincides with the onset of the Late Stone Age in Africa, a change in material culture that many archaeologists believe heralds the beginning of fully modern human behavior, including abstract thought and complex spoken language.

Paleontologist Meave Leakey, added: “Who would have thought that as recently as 70,000 years ago, extremes of climate had reduced our population to such small numbers that we were on the very edge of extinction.”

A praying mantis trapped in amber that was found in Japan in January 2008 dates back 87 million years, to the late Cretaceous period.

Researchers say the mantis, one of only seven in the world from this geologic period, displays unique features that may mean it is a "missing link" between the ancient insects and their modern counterparts.

Tuesday, April 22, 2008

Most of us are happy to admit that we do not understand, say, string theory in physics, yet we are all convinced we understand evolution. In fact, as biologists are discovering, its consequences can be stranger than we ever imagined. Evolution must be the best-known yet worst-understood of all scientific theories.

It will soon be 200 years since the birth of Charles Darwin and 150 years since the publication of On the Origin of Species, arguably the most important book ever written. In it, Darwin outlined an idea that many still find shocking – that all life on Earth, including human life, evolved through natural selection.

Darwin presented compelling evidence for evolution in On the Origin and, since his time, the case has become overwhelming. Countless fossil discoveries allow us to trace the evolution of today's organisms from earlier forms. DNA sequencing has confirmed beyond any doubt that all living creatures share a common origin. Innumerable examples of evolution in action can be seen all around us, from the pollution-matching pepper moth to fast-changing viruses such as HIV and H5N1 bird flu. Evolution is as firmly established a scientific fact as the roundness of the Earth.

And yet despite an ever-growing mountain of evidence, most people around the world are not taught the truth about evolution, if they are taught about it at all. Even in the UK, the birthplace of Darwin with an educated and increasingly secular population, one recent poll suggests less than half the population accepts evolution.For those who have never had the opportunity to find out about biology or science, claims made by those who believe in supernatural alternatives to evolutionary theory can appear convincing. Meanwhile, even among those who accept evolution, misconceptions abound.

New Scientist presents 24 concise articles on various misconceptions about evolution and creationist myths HERE.

Yes, I know the blog is supposed to be on hiatus (and it is), but the miserable weather here in Alberta has messed up my travel and research plans. Rather than be one more car in the ditch I'm staying off the highways and working from my home-away-from-home here in Edmonton for at least another day.

Monday, April 21, 2008

Typically for this time of year, Edmonton (where I am now) and the southern part of Alberta is under a winter weather warning, so I’m staying off the highways until they clean up the roads. Here’s a view out of my window this morning.

Sunday, April 20, 2008

Hennig is best known for developing phylogenetic systematics, a coherent theory of the investigation and presentation of the relations that exist among species. Contrary to the position generally held during his time, Hennig viewed historical inference as a strictly logical and scientific endeavor. He first summarized his ideas in 1950 in German which became more widely known with the publication of the English revision, Phylogenetic Systematics (Hennig, 1966).

1. Relationships among species are to be interpreted strictly genealogically, as sister-lineages, as clade relations. Empirically, a phylogenetic hypothesis may be determined.

2. Synapomorphies provide the only evidence for identifying relative recency of common ancestry. Synapomorphies are understood to be the shared-derived (evolved, modified) features of organisms.

3. Maximum conformity to evidence is sought (his auxiliary principle). Choice among competing cladistic propositions (cladograms) is decided on the basis of the greatest amount of evidence, the largest number of synapomorphies explainable as homologues.

4. Whenever possible, taxonomy must be logically consistent with the inferred pattern of historical relationships. The rule of monophyly is to be followed, thereby each clade can have its unique place in the hierarchy of taxonomic names.

Logan was a Canadian geologist dubbed the "Father of Canadian Geology." He began is career making geologic maps of coalfields in Wales, noting the relationship between the underlying clay layers and fossil tree roots with local coal beds. This substantiated the theory that coal beds are formed in place.

When he began as director (1842-69) of the new Geological Survey of Canada, its geology was virtually unknown. He produced the monumental Report on the Geology of Canada (1863) which recorded 20 years of research, fieldwork, plotting maps, preparing reports, and examining fossil and mineral specimens.

Erasmus was a prominent English physician, poet, philosopher, botanist, naturalist and the grandfather of naturalist Charles Darwin and the biologist Francis Galton. Erasmus Darwin was one of the leading intellectuals of 18th century England.

As a naturalist, he formulated one of the first formal theories on evolution in Zoonomia, or, The Laws of Organic Life (1794-1796). Although he did not come up with natural selection, he did discuss ideas that his grandson elaborated on sixty years later, such as how life evolved from a single common ancestor, forming "one living filament".

Although some of his ideas on how evolution might occur are quite close to those of Lamarck, Erasmus Darwin also talked about how competition and sexual selection could cause changes in species.link

“A rare Triceratops skeleton failed to find a buyer at a Christie's auction in Paris Wednesday after the top bid of 490,000 euros (782,000 dollars) fell short of the price sought by the dinosaur's owner. Christie's said it would over the coming two weeks still entertain post-auction offers for the massive three-horned dinosaur specimen that was the star attraction at the paleontology auction.

The auction on Wednesday marks the first time that such a dinosaur specimen has gone up for public sale since a T-Rex called "Sue" was sold in New York in October 1997. A sabre-toothed tiger cranium was sold for 72,000 euros, while a mammoth skull fetched 64,000 euros.

The auction has been criticized for encouraging private collectors to buy up artefacts of potential value to science. "This is part of our worldwide heritage," said Christian de Muizon, from the National Museum of Natural History in Paris.”

Moeritherium lived some 37 million years ago, many millions of years after the genetic lineages of elephants and sirenians split. Moeritherium didn't much resemble modern elephants. It was probably about the size of a tapir—74 to 107 cm tall --at the shoulder. It seems to have lacked a trunk but may have had a prehensile upper lip.

The spruce tree has shown to be a tenacious survivor that has endured by growing between erect trees and smaller bushes in pace with the dramatic climate changes over time.

A fascinating discovery was made under the crown of a spruce in Fulu Mountain in Dalarna. Scientists found four “generations” of spruce remains in the form of cones and wood produced from the highest grounds.

The discovery showed trees of 375, 5,660, 9,000 and 9,550 years old and everything displayed clear signs that they have the same genetic makeup as the trees above them. Since spruce trees can multiply with root penetrating braches, they can produce exact copies, or clones.

The tree now growing above the finding place and the wood pieces dating 9,550 years have the same genetic material. The actual has been tested by carbon-14 dating at a laboratory in Miami, Florida, USA. Previously, pine trees in North America have been cited as the oldest at 4,000 to 5,000 years old.

Sloane was a British physician and naturalist whose collection of books,manuscripts, and curiosities formed the basis for the British Museum in London. By the time he died, Sloane had amassed one of the world's largest and most varied collections of natural history specimens. His passion for the collection and his concern for its future upkeep after his death led him to write a will which clearly stated that it must "remain together and not be separated."

He offered it to the British nation, requesting in return a sum of £20,000 for his heirs. Parliament accepted, and King George II gave his royal assent 7 Jun 1753. Thus the British Museum was created and eventually its sister institution, the British Museum of Natural History. image

Buffon was a French naturalist, who formulated a crude theory of evolution and was the first to suggest that the earth might be older than suggested by the Bible. In 1739 he was appointed keeper of the Jardin du Roi, a post he occupied until his death. There he worked on a comprehensive work on natural history, for which he is remembered, Histoire naturelle, générale et particulière. He began this work in 1749, and it dominated the rest of his life. It would eventually run to 44 volumes, including quadrupeds, birds, reptiles and minerals. He proposed (1778) that the Earth was hot at its creation and, from the rate of cooling, calculated its age to be 75,000 years, with life emerging some 40,000 years ago.

Monday, April 14, 2008

It is with deepest regret to announce the passing away of Dr. Yaoming Hu on April 12, 2008, at the age of 42 years, after a heavy illness. He was born on October 27, 1966 in Jiangsu, China. In 1988 he graduated from the Department of Geology of the Peking University, after a four years course in Geology. He was granted the degree of Master of Paleontology in the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences in 1992, and the Ph. D. in Biology in the City University of New York in 2006.

Beginning in 1992 Yaoming was working at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, as a Research Assistant, an Assistant Research Professor, Associate Research Professor, and a Research Professor. During his scientific life he was engaged in studies on the Mesozoic and Paleogene mammals of China and became a well-known specialist on them. His contributions cover the anatomy, phylogeny, systematics, biostratigraphy and related issues of many Paleogene and Mesozoic mammal groups, including anaglids, yuomyid rodents, rhombomylid glires, leporid and ochotonid lagomorphs, repenomamid and gobiconodontid triconodonts, eobaatarid multituberculates, spalacotheriid symmetrodonts, and the gliding volaticotheriid, etc.

Yaoming has been a hard worker, entirely devoted to science. He had a very kind, serene and modest character, with unusual sense of humor. He had a happy family life with his wife Yanjie, and left behind a four-year-old son. He will be missed and long remembered by those of us who knew and loved him.

The fearsome Komodo dragon is the world's largest living lizard and can take very large animal prey: now a new international study has revealed how it can be such an efficient killing machine despite having a wimpy bite and a featherweight skull.

The Komodo dragon (Varanus komodoensis) grows to an average length of two to three metres and weighing around 70 kilograms. The reptile's unusual size is attributed to island gigantism, since there are no other carnivorous mammals to fill the niche on the islands where they live. As a result of their size, these lizards are apex predators, dominating the ecosystems in which they live. Although Komodo dragons eat mostly carrion, they will also hunt and ambush prey including invertebrates, birds, and mammals.

With ancestors dating back more than 100 million years, the dragon uses a combination of 60 razor-sharp serrated teeth, powerful neck muscles and what researchers are calling a "space-frame" skull to butcher prey with awesome efficiency, the study found.

They note that the dragon – inhabiting the central Indonesian islands of Komodo, Rinca, Flores, Gili Motang and Gili Dasami – shares the feeding and dental characteristics of extinct dinosaurs, sharks and sabre-toothed cats. Scientists have used a computer-based technique called Finite Element Analysis (FEA) to test the bite force and feeding mechanics of the predator. The results will be published in an upcoming issue of the Journal of Anatomy.

"The Komodo has a featherweight, space-frame skull and bites like a wimp," according to Wroe, "but a combination of very clever engineering, and wickedly sharp teeth, allow it to do serious damage to even buffalo-sized prey.

“The Komodo displays a unique [really, what about most predatory birds? ed.] hold and pull-feeding technique," says Dr Wroe. "Its delicate skull differs greatly from most living terrestrial large prey specialists, but it’s a precision instrument, beautifully optimised to make the most of its natural cranial and dental properties.

"Unlike most modern predators, Varanus komodoensis applies minimal input from the jaw muscles when killing and butchering prey. But it compensates using a series of actions controlled by its postcranial muscles. A particularly interesting feature of the skull's performance is that it reveals considerably lower overall stress when these additional forces driven by the neck are added to those of the jaw-closing muscles.

"What truly assured Cope's (above right) place in the history of paleontology and even eclipsed his science was his bitter feud with Yale University paleontologist O.C. Marsh (above left). What began as a friendly rivalry in the late 1860s, broke out into all out war in 1872 and then raged on until Cope's death in 1897. Both Cope and Marsh were recipients of family fortunes and they used their wealth to discover new fossils and to reconstruct ancient life. This scramble literally propelled American science into the forefront of paleontology."

Scientists working on the technique used chemical signatures in seawater and ocean sediments to study the dino-killing impact that occurred at the end of the Cretaceous period, about 65 million years ago.

In what could be a major scientific puzzle, the team's new size estimate for the dino-killing meteorite is a mere 4 to 6 kilometers across. The most recent computer models predicted a size of 15 to 19 kilometers across.

Abstract: Decreases in the seawater 187Os/188Os ratio caused by the impact of a chondritic meteorite are indicative of projectile size, if the soluble fraction of osmium carried by the impacting body is known.

Resulting diameter estimates of the Late Eocene and Cretaceous/Paleogene projectiles are within 50% of independent estimates derived from iridium data, assuming total vaporization and dissolution of osmium in seawater. The variations of 187Os/188Os and Os/Ir across the Late Eocene impact-event horizon support the main assumptions required to estimate the projectile diameter.

Chondritic impacts as small as 2 kilometers in diameter should produce observable excursions in the marine osmium isotope record, suggesting that previously unrecognized impact events can be identified by this method.

Abstract: The extreme warmth of particular intervals of geologic history cannot be simulated with climate models, which are constrained by the geologic proxy record to relatively modest increases in atmospheric carbon dioxide levels.

Recent recognition that biological productivity controls the abundance of cloud condensation nuclei (CCN) in the unpolluted atmosphere provides a solution to this problem.

Our climate simulations show that reduced biological productivity (low CCN abundance) provides a substantial amplification of CO2-induced warming by reducing cloud lifetimes and reflectivity. If the stress of elevated temperatures did indeed suppress marine and terrestrial ecosystems during these times, this long-standing climate enigma may be solved.

Abstract: Long-held ideas regarding the evolutionary relationships among animals have recently been upended by sometimes controversial hypotheses based largely on insights from molecular data. These new hypotheses include a clade of moulting animals (Ecdysozoa) and the close relationship of the lophophorates to molluscs and annelids (Lophotrochozoa).

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The figured topology and branch lengths are for the sampled tree with the highest likelihood (1,000 searches, log likelihood = –796,399.2). Support values are derived from 1,000 bootstrap replicates. Leaf stabilities are shown in blue above each branch. Taxa for which we collected new data are shown in green.

Many relationships remain disputed, including those that are required to polarize key features of character evolution, and support for deep nodes is often low. Phylogenomic approaches, which use data from many genes, have shown promise for resolving deep animal relationships, but are hindered by a lack of data from many important groups.

Here we report a total of 39.9 Mb of expressed sequence tags from 29 animals belonging to 21 phyla, including 11 phyla previously lacking genomic or expressed-sequence-tag data. Analysed in combination with existing sequences, our data reinforce several previously identified clades that split deeply in the animal tree (including Protostomia, Ecdysozoa and Lophotrochozoa), unambiguously resolve multiple long-standing issues for which there was strong conflicting support in earlier studies with less data (such as velvet worms rather than tardigrades as the sister group of arthropods), and provide molecular support for the monophyly of molluscs, a group long recognized by morphologists.

In addition, we find strong support for several new hypotheses. These include a clade that unites annelids (including sipunculans and echiurans) with nemerteans, phoronids and brachiopods, molluscs as sister to that assemblage, and the placement of ctenophores as the earliest diverging extant multicellular animals.

A single origin of spiral cleavage (with subsequent losses) is inferred from well-supported nodes. Many relationships between a stable subset of taxa find strong support, and a diminishing number of lineages remain recalcitrant to placement on the tree.

One of the steps in turning genetic information into proteins leaves ‘genetic fingerprints’, even on regions of the DNA that are not involved in coding for the final protein. They estimate that such fingerprints affect at least a third of the genome, suggesting that while most DNA does not code for proteins, much of it is nonetheless biologically important – important enough, that is, to persist during evolution.

To gauge how critical a particular stretch of DNA is, biologists often look at the detailed sequence of “letters” it consists of, and compare it with a corresponding stretch in related creatures like mice. If the stretch serves no purpose, the thinking goes, the two sequences will differ because of numerous mutations since the two species last shared an ancestor. In contrast, it’s believed that the sequences of important genes will be similar, or “conserved,” in different species, because animals with mutations in these genes did not survive. Biologists therefore regard conserved sequences as a sign of biological importance.

Even within a gene, stretches of DNA that code for pieces of the target protein are usually interspersed with much larger noncoding stretches, called introns, that are removed from the RNA working copy of the DNA before the protein is made.

Previous researchers assumed that mutations in the middle of introns do not affect the final protein, so they simply accumulate. In the new work, however, the researchers found signs that evolution rejects some types of mutations even in these regions of the genome. Although the selection is weak, “introns are not neutral,” in their effect on survival, says Michael Zhang.

The scientists found a preference for some “letters” across intron regions, and the opposite preference in coding regions. Together, these regions make up at least a third of the genome, which is thus under selective pressure during evolution. The result supports other recent studies that suggest that, although most DNA does not code for proteins, much of it is nonetheless biologically important.

Abstract: Criteria for designating dinosaur genera are inconsistent; some very similar species are highly split at the generic level, other anatomically disparate species are united at the same rank. Since the mid-1800s the classic genus Iguanodon has become a taxonomic grab-bag containing species spanning most of the Early Cretaceous of the northern hemisphere. Recently the genus was radically redesignated when the type was shifted from nondiagnostic English Valanginian teeth to a complete skull and skeleton of the heavily built, semi-quadrupedal I. bernissartensis from much younger Belgian sediments, even though the latter is very different in form from the gracile skeletal remains described by Mantell.

Currently, iguanodont remains from Europe are usually assigned to either robust I. bernissartensis or gracile I. atherfieldensis, regardless of location or stage. A stratigraphic analysis is combined with a character census that shows the European iguanodonts are markedly more morphologically divergent than other dinosaur genera, and some appear phylogenetically more derived than others.

Two new genera and a new species have been or are named for the gracile iguanodonts of the Wealden Supergroup:

1. The strongly bipedal Mantellisaurus atherfieldensis Paul (2006. Turning the old into the new: a separate genus for the gracile iguanodont from the Wealden of England. In: Carpenter, K. (Ed.), Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Indiana University Press, Bloomington, pp. 69–77) (holotype BMNH R5764) which possesses a camptosaur-like ilial shape,

2. The long snouted, long bodied, small hipped, semi-bipedal Dollodon bampingi gen. nov. sp. nov.(holotype IRSNB 1551) which has a shallow ilium.

Insufficiently diagnostic I. hoggii is removed from the earlier Camptosaurus. Poorly described I. dawsoni, I. fittoni and I. hollingtoniensis are removed from the much later and more derived Iguanodon and considered Ornithopoda incertae sedis pending redescription. The synonymy of I. fittoni and I. hollingtoniensis has not been confirmed.

A set of remains of similar age to I. fittoni and I. hollingtoniensis appear to combine a specialized, elongate dentary with massive arms: it either belongs to one of the contemporary taxa, or is a new, unnamed taxon.

There has recently been a tendency to consider iguanodonts spatially remote from I. bernissartensis to be members of or very similar to the type species, but reanalysis finds that I. orientalis is not a junior synonym of I. bernissartensis and is a nomen dubium, and that basal I. lakotaensis is not a member of Iguanodon and accordingly is assigned the new genus Dakotadon gen. nov. (holotype SDSM 8656).

Dakotadon is probably basal to Iguanodon and not an iguanodontoid. The higher taxonomy of iguanodontoids is confused due to phylogenetic problems, and inconsistent definitions of the Iguanodontidae (which as currently defined appears to be limited to Iguanodon) and Hadrosauroidea. Mantellisaurus and especially Dollodon, for instance, are probably more derived than Iguanodon: they may be hadrosauroids depending on which phylogenetic definition of the term is preferred.

Monday, April 07, 2008

In a report at the 235th national meeting of the American Chemical Society, Ronald Breslow, described how our “left-handed” amino acid signature came from outer space.

Chains of amino acids make up the protein found in people, plants, and all other forms of life on Earth. There are two orientations of amino acids, left and right, which mirror each other, known as “chirality.” In order for life to arise, proteins must contain only one chiral form of amino acids, left or right.

With the exception of a few right-handed amino acid-based bacteria, left-handed “L-amino acids” dominate on earth. The amino acids delivered to Earth by meteorite bombardments left us with those left-handed protein units.

“These meteorites were bringing in what I call the ‘seeds of chirality,’” stated Breslow. These amino acids “seeds” formed in interstellar space, possibly on asteroids as they careened through space. At the outset, they have equal amounts of left and right-handed amino acids. But as these rocks soar past neutron stars, their light rays trigger the selective destruction of one form of amino acid. The stars emit circularly polarized light—in one direction, its rays are polarized to the right. 180 degrees in the other direction, the star emits left-polarized light.

All earthbound meteors catch an excess of one of the two polarized rays. Breslow said that previous experiments confirmed that circularly polarized light selectively destroys one chiral form of amino acids over the other. The end result is a five to ten percent excess of one form, in this case, L-amino acids. Evidence of this left-handed excess was found on the surfaces of these meteorites, which have crashed into Earth even within the last hundred years, landing in Australia and Tennessee.

On the prebiotic Earth, this transfer left a slight excess of left-handed amino acids, Breslow said. Experimental evidence indicates that only a 5% excess of left-handed amino acids was enough for it to become ubiquitous as it was used selectively by living organisms. link

Sunday, April 06, 2008

The museum began from the efforts of Albert Smith Bickmore, one-time student of Harvard zoologist Louis Agassiz, who was successful in his proposal to create a natural history museum in New York City, with the support of William E. Dodge, Jr., Theodore Roosevelt, Sr., Joseph Choate, and J. Pierpont Morgan. It opened to the public 27 Apr 1871.

With a series of exhibits, the Museum’s collection went on view for the first time in the Central Park Arsenal, the Museum’s original home, on the eastern side of Central Park.

Also, on this day in 1930, Hostess Twinkies were invented by bakery executive James Dewar.

Saturday, April 05, 2008

A monument will be erected to the famous "Beatles" group in Ulaanbaatar city, the capital of Mongolia.

In support of the initiative, Prime Minister S.Bayar attended Friday a news conference called on this matter. Saying that the Beatles launched a globalization process, Mr. Premier told that he has been listening the Beatles' sings for over 40 years.

Standing close to a guitar sculptures of four "Beatles" will be made of bronze. Songs of Beatles and of Mongolian groups and singers will sound all day through. Over MNT 100 million is required for this project. On April 26, a donation concert will be given.I checked the date of this and it was not April 1st. Original link here.

In 1753, the British Museum was founded by an Act of Parliament. Since then, the museum has been collecting, conserving and studying millions of artifacts. The British Museum was among the first museums to recognize that in-house scientific expertise was essential, both for the care of its collections and for their proper interpretation. Its Research Laboratory was founded in 1920 with the appointment of Dr Alexander Scott as its first scientist.

Abstract: Few species have generated more or longer running controversy than Australia's extinct marsupial lion Thylacoleo carnifex (Owen, 1859). Over the last century and a half, feeding behaviours as disparate as osteophagy and specialized herbivory have been suggested and T. carnifex has been placed in both phalangeriform and vombatiform clades.

Phylogenetic placement remains uncertain, but broad consensus has been achieved regarding diet, with all recent authors agreeing that T. carnifex was a carnivore. However, the marsupial lion's extraordinary cranial and dental morphologies remain without clear analogy, leaving many questions unanswered regarding how this most atypical mammalian predator killed its prey.

Here I apply a rapidly emerging new approach in comparative biology, finite-element analysis, to the examination of cranial mechanics in T. carnifex. Comparisons are made with an extant lion Panthera leo (Linnaeus, 1758) under simulations designed to model stress distributions imposed by biting (intrinsic loads) and interaction with struggling prey (extrinsic loads).

Modelling that approximates the 3-D architecture of jaw adductors suggests that both the placental and marsupial lions could generate considerably greater bite forces than has been predicted using 2-D approaches, but with relatively greater forces in the marsupial. The distribution of cranial stress is in many respects similar in both species, but results from simulations of extrinsic forces suggest that the marsupial was particularly well adapted to resist the high stresses that would be expected in dealings with relatively large prey.

On the other hand, relatively high stress recorded in the rostrum of T. carnifex under intrinsic loadings suggests that it may have deployed a very different modus operandi, wherein the carnassial teeth played an active role in effecting a kill.

Thursday, April 03, 2008

English geologist who was a leading authority on the mechanics of sediment transport, especially eolian (wind) transport. While serving as a soldier in Egypt prior to WW II, Bagnold first studied sand dune formation and movement. After retiring from the army (1935), he continued his research and wrote the book "Physics of Blown Sand and Desert Dunes", investigating the physics of particles moving through the atmosphere and deposited by wind.

He recognized two basic dune types, the crescentic dune, which he called "barchan," and the linear dune, which he called longitudinal or "sief" (Arabic for "sword"). During WW II, his avocational interest in vehicle performance on blowing sand aided the Allies in North Africa.

If you’re in Cleveland today, Dr. Jeff Wilson from Michigan State University University of Michigan is giving a Biology departmental seminar at 4:15pm, DeGrace Hall, Rm 312 on the Case Western Reserve Campus.

Update: Jeff gave a great talk, as usual! I owe him dinner (at least!) for making him wait to meet up with me this morning. Sorry again, Jeff!

The Conference will follow the Symposium of Vertebrate Palaeontology being hosted by the University of Bristol (U.K.) during 23 - 26 September 2009, in order to offer to participants from all over the world the opportunity to attend two meetings while in Europe.

Wednesday, April 02, 2008

In the first experiment of its kind conducted in nature, an evolutionary biologist has come up with strong evidence for one of Charles Darwin’s cornerstone ideas – adaptation to the environment accelerates the creation of new species.

“A single adaptive trait such as color could move a population towards the process of forming a new species, but adaptation in many traits may be required to actually complete the formation of an entirely new species,” says Patrik Nosil. “The more ways a population can adapt to its unique surroundings, the more likely it will ultimately diverge into a separate species.”

Nosil studied walking-stick insects in the Santa Barbara Chaparral in southern California. Stick insects cannot fly and live and feed on their host plants. Different “eco-types” of walking-stick insects are found on different plants and exhibit different color patterns that match the features of their host plants. For example, insects of the cristinae eco-type, which feed on plants with needle-like leaves, have a white line along their green bodies.

By displacing some eco-types away from their customary host plants and protecting others from their natural predators, Nosil found that color pattern alone could initiate speciation, while natural selection on additional adaptive traits such as the ability to detoxify different host-plant chemicals are required to “seal the deal,” or complete the speciation process initiated by differences in color pattern.

“Natural selection has been widely regarded as the cause of adaptation within existing species while genetics and geography have been the focus of most current research on the driving force of speciation,” says Nosil.

It is with deepest regret to announce the death of Professor Halszka Osmólska on March 31, 2008, at the age of 78 years, after a heavy illness. She was born on September 15, 1930 in Poznań, Poland. In 1952 she graduated from the Faculty of Biology and Earth Sciences of the Poznań University, after a three years course in biology, and then moved to Warsaw, where in 1955 she was granted the degree of Master of Biological Sciences at the University of Warsaw, and in 1962 the Ph. D. in Biological Sciences at the Faculty of Geology of the same University.

Beginning with 1955 she was working at the Institute of Paleobiology of the Polish Academy of Sciences in Warsaw, as an assistant professor, associate professor, docent and a full professor. In 1974 -- 1983 she was the deputy director of the Institute, and in 1984-1989 the director. In 1975 -- 1992 she was the editor of /Acta Palaeontologica Polonica/. She was a member of various scientific societies and committees.

During the first half of her scientific life she was engaged in studies on the Late Devonian and Carboniferous trilobites of Poland and Eurasia and became a well-known specialist on them. Beginning with 1969 she changed her scientific interests and started to study the Late Cretaceous dinosaurs and other reptiles from the Gobi Desert, and soon became an authority in this field. She was a co-author and co-editor (with David W, Weishampel and Peter Dodson) of the famous book "The Dinosauria", published by the University of California Press. The first edition of the book was published in 1990, the second in 2004.

Halszka has been a hard worker, entirely devoted to science. She had a very kind and serene character, with unusual sense of humor, and modesty. She had a long and happy family life with her late husband Tadeusz, and left behind the son, daughter-in-law, and three grandchildren. She will be missed and long remembered by those of us who knew and loved her.

On this day in 1953, the journal Nature published a paper from Francis Crick and James Watson, titled Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid, in which they described a double helix structure for DNA.

Paleontologists have applied to opaque amber a synchrotron X-ray imaging technique known as propagation phase contrast microradiography to look into the interior of opaque amber. Once discovered on the radiographs, some of the organisms were imaged in three dimensions and virtually extracted from the resin.

The scientists imaged 640 pieces of amber from the Charentes region in southwestern France. They discovered 356 fossil animals, going from wasps and flies, to ants or even spiders and acarians. The team was able to identify the family of 53% of the inclusions.

Most of the organisms discovered are tiny. For example, one of the discovered acarians measures 0.8 mm and a fossil wasp is only 4 mm. “The small size of the organisms is probably due to the fact that bigger animals would be able to escape from the resin before getting stuck, whereas little ones would be captured more easily”, explains Malvina Lak.